Polymer-, organic-, and molecular-based spintronic devices

ABSTRACT

This invention relates to organic based spintronic devices, and electronic devices comprising them, including spin valves, spin tunnel junctions, spin transistors and spin light-emitting devices. New polymer-, organic- and molecular-based electronic devices in which the electron spin degree of freedom controls the electric current to enhance device performance. Polymer-, organic-, and molecular-based spintronic devices have enhanced functionality, ease of manufacture, are less costly than inorganic ones. The long spin coherence times due to the weak spin-orbit interaction of carbon and other low atomic number atoms that comprise organic materials make them ideal for exploiting the concepts of spin quantum devices. The hopping mechanism of charge transport that dominates in semiconducting polymers (vs. band transport in crystalline inorganic semiconductors) enhances spin-magneto sensitivity and reduces the expected power loss.

[0001] This Application claims the benefit of U.S. ProvisionalApplication No. 60/243,970, filed Oct. 27, 2000, which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

[0002] This invention relates to organic based spintronic devices, andelectronic devices comprising them, such as spin valves (such as thoseshown in FIGS. 1 and 3), spin tunnel junctions, spin transistors andspin light-emitting devices that use the arrangements of the presentinventions.

BACKGROUND AND SUMMARY OF THE INVENTION

[0003] 1. Innovation and Concepts

[0004] New polymer-, organic- and molecular- based electronic devices inwhich the electron spin degree of freedom controls the electric currentto enhance device performance provide a key basis for a broad range oftechnologies. Polymer-, organic-, and molecular-based spintronic deviceshave enhanced functionality, ease of manufacture, are less costly thaninorganic ones. The long spin coherence times due to the weak spin-orbitinteraction of carbon and other low atomic number atoms that compriseorganic materials make them ideal for exploiting the concepts of spinquantum devices. The hopping mechanism of charge transport thatdominates in semiconducting polymers (vs. band transport in crystallineinorganic semiconductors) enhances spin-magneto sensitivity and reducesthe expected power loss.

[0005] Introduction: In the past decade there has been extensiveprogress in inorganic multilayer based spin valves.¹ Giant magneticresistance and spin valves based on this effect recently enabled 100%per year growth of the areal density in the hard drive disk industry.²Recent extensions to magnetic semiconductor-based spin valves³ andrelated spin-LEDs⁴ have been shown to be promising embodiments ofspintronics; however, there are substantial problems due to interfacesas well as low Curie temperatures (T_(c)) for present magneticsemiconductors.⁵

[0006] There is growing interest in replacing inorganic electronicmaterials with inexpensive, easier-to-fabricate polymers akin to theinterest in using conducting polymers in a myriad of electronicapplications.⁶ Many polymer/molecular/organic materials can be dissolvedin solution and spun into thin films or readily evaporated onto manysubstrates. This is anticipated to lead to cost efficiency and ease ofmanufacture in devices, especially for large area use and flexiblesubstrates. Also, electronic polymers are known to be radiation hard.Another advantage of molecular/organic materials is the richness ofchemistry which enables the synthesis of materials with very specificproperties. Recently it was demonstrated⁷ that organic molecules can beused to create nano-sized heterojunctions and as building blocks for amolecular computer.⁸

[0007] Today, selected polymers readily conduct electric charge.⁹ Theroom-temperature conductivity σ_(RT) of conjugated polymers, such aspolyacetylene, polyaniline, and polypyrrole, can be controlled over 15decades by doping and structural order and attain a value that is onlyan order of magnitude below the record conductivity of superpure Cu(σ_(RT)=6×10⁵S/cm).

[0008] Since the report in 1990 of electroluminescence¹⁰ in the lightemitting polymer (LEP) PPV, there have been many advances in polymerlight-emitting diodes. Polymer/molecule based LEDs in all wavelengths oflight¹¹ (from ir to uv) and with a wide variety of output parameters areknown¹² and commercialization of polymer LEDs has begun.¹³

[0009] Molecule-based magnetism started with the discovery¹⁴ in the mid1980's of ferromagnetism at 4.8 K in the linear chain of electrontransfer salt [FeCp*₂][TCNE] (Cp*=pentamethylcyclopendienide;TCNE=tetracyanoethylene) by Miller and Epstein. Today there is“polymeric” material such as V[TCNE]_(x) (x˜2) that is room temperaturemagnet and which is processable at room temperature by usingconventional organic chemistry, common solvents, and low temperaturechemical vapor deposition (CVD).¹⁵ V[TCNE]_(x) is a ‘soft’ magnet withmagnetic ordering temperature T_(c)=400 K, a small coercive fieldH_(c)=4.5 Oe (varying by more that one order of magnitude with detailsof preparation/processsing) at 300 K, and semiconducting conductivityσ_(RT)˜10⁻⁵ S/sm. Other examples of polymer/molcule/organgic basedmagnets include Prussian Blue(s). Examples of Prussian Blue(s)structure-containing compounds include V[Cr(CN)₆]_(x)•YH₂O, where x isbetween 0.5 and 1.5; preferably 0.8 to 1.2, and Y is between 0 and 4;preferably 1.5 and 2.8.

[0010] Approach/Innovative Concepts: We propose the concept ofspintronics in polymer devices as all the mandatory elements can beachieved with polymers. A key argument for exploiting polymerspintronics is the very long spin coherence time (τ_(s)) in polymers.Analysis of EPR data yields 10⁻⁷ s for poorly conducting polymers¹⁶ andmicroseconds for well-conducting samples.¹⁷ Also, τ_(s) is 10⁻⁸ S forV[TCNE]_(x) ¹⁸, which is longer than that of conventional inorganicsemiconductors ˜10⁻⁹ s. Polymers enable us to overcome difficulties thatinorganic spintronics faces such as poor spin injection through theinterfaces, low Curie temperature, and low sensitivity. Preliminarymeasurements yield low barriers to charge injection between magnetic andconducting polymers. Table 1 is a comparative summary of semiconductorand polymer-based magnet parameters. TABLE 1 Example comparison ofinorganic and polymer magnetic semiconductors parameters Polymer-Semiconduct based or Magnets Magnets T_(C) 90 K 400 K H_(C) 40 Oe at 6K4.5 oE at 300K σ_(RT) 10⁻⁵ S/cm 10⁻⁵ S/cm ΔG/G of 0.1% at 300K 40% at300K spin-value 0.3% at 77K (anticipated) τ_(s) 10⁻⁹ s 10⁻⁸ s InterfacesRigid Flexible, inter- penetrating Processing High (typically Low (<40°C.) T >600° C.)

[0011] The schematic layout of a vertical polymer-based magneto-spingate (spin-valve) is shown in FIG. 1. The resistance of the sandwichstructure (Hard Magnet—Conductor—Soft Magnet) strongly depends on therelative orientation of the magnetization of hard and soft magnets. Thehard magnet aligns spins of electrons injected from the metal contact.The transit time for electrons across the central conductor is shorterthan the spin coherence time; therefore, if the magnetization of thesoft magnet is aligned with that of the hard magnet, electrons easilycontinue their path to reach another electrode. For oppositemagnetization of the soft magnet, transit of the polarized electrons isforbidden unless the spins reorient. The conducting layer in the centerserves as a spacer to separate soft and hard magnets, thus, enabling thesoft magnet to be tunable by an external magnetic field.

[0012] Estimates of the parameters and characteristics of a polymerspin-valve vary depending on mechanism of charge transport. In highlyconducting polymers (σ_(RT)≧100 S/cm) the room-temperature conductivityis provided by metallic band-like motion, with charge hopping overnearest neighbor states.¹⁹ Then the hopping rate ω_(h) is given by thetypical phonon frequency 10¹² s⁻¹ and the length of hopping L_(hop) isthe localization radius ξ, which is given by scale of inhomogenieties,typically 2 nm. Taking the spin coherence time τ_(s) as 10⁻⁷ s we findthat the electron makes N_(h)˜10⁵ hops before the electron loses itsspin orientation. Hence, the spin coherence length can be estimated asL_(coherence)≈L_(hop)×{square root}N_(h)˜1 μm.

[0013] If the poorly conducting polymers (τ_(RT)≦10⁻¹ S/cm) are used,the Mott variable range hopping (VRH) mechanism of transport dominates.In this case the hopping rate is essentially decreased, butsimultaneously the length of hopping increases; therefore, on the wholethe coherence length L_(coherence) remains at the micron scale at leastfor room temperature. It is important to have L_(coherence) large, asthis parameter controls the effectiveness of the device and the spincoherence length also limits the allowed thickness of conducting layerL_(c)<L_(coherence). For a hard magnet, a metallic ferromagnetic orferrimagnetic or similar film may be used. In soft polymeric magnets,such as V[TCNE]_(x), charge motion is by hopping and the hoppingdistance is determined by the disorder. We estimate the hopping lengthas 10 nm. The thickness of the soft magnet L_(S) should be at least afew hopping distances, i.e., L_(S)>>10 nm. Other polymer, organic ormolecule based magnets may be used, including those with spins inorganic groups only, those with spins on metals and on organics, andthose with spins only on inorganic groups connect through spinlessorganic groups. It is noted that nearly fully spin polarized transportmay be achieved by use of ferrimagnetic order between to groups ofdifferent ionization energy. For example, for V[TCNE]_(x), the spin 3/2of the V is opposite to the spin ½ of the TCNE. This leads to the chargecarriers (coming from the TCNE) being polarized (up to 100% polarized ifx=2). To read a magnetic memory, the external field for the soft magnetshould be a few Gauss. V[TCNE]_(x) with coercive force 4.5 Oe is closeto this requirement.

[0014] We estimate the potential sensitivity of polymer spin-valves asfollows. Through changing the magnetic polarization of the soft magnetfrom parallel to antiparallel with respect to the hard magnet, theactivation energy for electrons in the soft magnet area increases.Therefore, the change of conductance ΔG with polarization is given byΔG/G=(1−exp[−ΔE/(k_(B)T)]), where G is the conductance of the device. Weassume that G is determined by the soft magnetic layer which is the mostresistive part of sandwich. ΔE is the activation energy, which is givenby the internal field H_(i) of the soft magnet: ΔE=gμ_(B)H_(i).According to mean field theory, H_(i) is temperature dependent²⁰, and,therefore, ΔE=k_(B)T_(c)(1−T/T_(c))^(½), where T_(c) is the temperatureof magnetic ordering. For T_(c)=400 K and T=300 K we obtain ΔG/G=40%.The above estimate gives an approximate scale for sensitivity,neglecting the thickness of soft magnetic film and the energy disorderby considering it as a monolayer with one hopping energy. FIG. 2presents promising initial bulk magnetoresistance for CVD-preparedV[TCNE]_(x) film, recording an ˜0.3% change in resistance at roomtemperature for an applied field of 6 kOe.

[0015] For magnetic memory applications, e.g., read heads and magneticrandom access memories, the current in plane (CIP) spin-valveconstruction, FIG. 3, is common. Here we replace the hard magnet layerwith a polymer, molecule or organic based soft magnet polarized by thehard magnet. The central conducting spacer will be thin so that thetotal conductance principally is determined by transport through thesoft magnet area. As σ_(RT) for V[TCNE]_(x) is ˜10⁻⁵ S/cm, lessconducting polymers with VRH conductivity will be used. Again as σ inpolymeric magnets is dominated by the activated hopping we expect thespin-magneto sensitivity to be very high and, perhaps, it can approachits maximum, ΔG/G=50%. The small absolute G guarantees low power loss ofdevice. For the polymer, organic or molecular based spin valve thenonmagnetic conductor may be an inorganic conductor or semiconductorsuch as copper or silicon, or an organic, molecular or polymer basedconductor such as doped polythiophene or doped polyaniline, orsemiconductor, such as undoped polythiophene, polyaniline, or tetracene.

[0016] Novel Polymer Spin LED: The schematic construction of anall-polymer Spin-LED, FIG. 4, has all central working elements made frompolymers. Typically transparent indium-tin oxide (ITO) with high workfunction is used as a hole-injecting electrode. Al can be chosen toserve as the cathode as its work function is small. The electronaffinity of V[TCNE]_(x) is expected to be close to the Fermi level ofAl. Spins of electrons injected from the Al contact are aligned by thestrong internal field of the polymer magnet. The orientation of theinternal magnetic field follows the weak applied external field. Thechoice of light-emitting polymer (LEP) is determined by the desiredwavelength of light and need for chirality and spin orbit coupling toachieve circularly polarized emission. Examples of spin LED emittersinclude rare earth metal containing polymers and metal complexes. Forexamples, Er containing molecules (for ir emission at 1.5 microns,important for fiber optic communications), green emitting Ir and Ptcontaining complexes for

[0017] Addition of rare earth ions with their large spin-orbit couplingwill increase the circularly polarized emission and quantum yield ofelectroluminescence. Chiral groups and dopants as as phosphorescent dyesmay also be used for achieving circularly polarized emission. Theprevailing spins in LEP can be detected by increase in one of thecircularly polarized components similar to magnetic circulardichroism.²² Thus the weak external magnetic field leveraged by the softmagnet and transferred by electrons into the optically active partfinally controls dichroism in the device. While T_(c)>300 K for themagnets is routinely achievable, the interfaces between magneticpolymers and other materials is important. Coating of the films with,for example, inert polymers enhances the longevity of films and devicesby making them more stable to ambient conditions. This includes greaterchemical stability to air, water, and solvents, as well as abrasionresistance.

[0018] Improved performance of next generation systems requires enhancedmagnetic polymers. Other organic, polymer, and molecule based thin-filmmagnets are based on other acceptors instead of TCNE. For example,V[TCNQ]_(x) (TCNQ=7,7,8,8-tetracyano-p-quinodimethane) forms thin filmmagnets and has different magnetic behaviors. Likewise, improvedmaterials are expected from optimization of the vanadium source for theV[TCNE]_(x) magnetic films. Studies in this area should also lead to newclasses of thin-film room-temperature magnets, e. g., V[Cr(CN)₆]_(x)electrochemically prepared.

[0019] Accordingly, the present invention includes spin valves (such asthose shown in FIGS. 1 and 3), spin tunnel junctions, spin transistorsand spin light-emitting devices that use the arrangements of the presentinventions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 shows the layout of a polymer-based spin-valve of thepresent invention.

[0021]FIG. 2 is a diagram of room temperature magnetoresistance forV[TCNE]_(X).

[0022]FIG. 3 is a diagram of a CIP spin-valve.

[0023]FIG. 4 shows the structure of all polymer Spin-LED emittingcircularly polarized light modulated by external magnetic field.

[0024] References:

[0025] 1. G. Prinz, Magnetoelectronics, Science 282, 1660-1663 (1998).

[0026] 2. S. Araki, et al., Which Spin Valve for Next GiantMagnetoresistance Head Generation? J. Appl. Phys. 87, 5377-5382 (2000).

[0027] 3. D. J. Monsma, et al., Room Temperature-Operating Spin-ValveTransistors Formed by Vacuum Bonding, Science 281, 407-409 (1998).

[0028] 4. R. Fiederling, et al., Injection and Detection of aSpin-Polarized Current in a Light-Emitting Diode, Nature 402, 787-790(1999); Y. Ohno, et al., Electrical Spin Injection in a FerromagneticSemiconductor Heterostructure, Nature 402, 790-792 (1999).

[0029] 5. H. Ohno, Making Nonmagnetic Semiconductors Ferromagnetic,Science 281, 951-956 (1998).

[0030] 6. C. J. Drury, et al., Low-Cost All-Polymer Integrated Circuits,Appl. Phys. Lett. 73, 108-110 (1998); R. F. Service, New AgeSemiconductors: Pick up the Pace, Science 287, 415-417 (2000); J. H.Schon, et al., Ambipolar Pentacene Field-Effect Transistors andInverters, Science 287, 1022-1023 (2000).

[0031] 7. J. Chen, et al., Large On-Off Ratios and Negative DifferentialResistance in a Molecular Electronic Device, Science 286, 1550-1551(1999); C. P. Collier, et al., Electronically ConfigurableMolecular-Based Logic Gates, Science 285, 391-394 (1999).

[0032] 8. A. Aviram and M. A. Ratner, Molecular Electronics: Science andTechnology, Ann. N.Y. Acad. of Sci, 1998; M. A. Reed, Molecular-ScaleElectronics, Proc. IEEE 87, 1999; R. M. Metzger, ElectricalRectification by a Molecule: The Advent of Unimolecular ElectronicDevices, Acc. Chem. Res. 32, 950-957 (1999).

[0033] 9. R. S. Kohlman and A. J. Epstein, Insulator-Metal Transitionand Inhomogeneous Metallic State in Conducting Polymers, Handbook ofConducting Polymers, Marcel Dekker, Inc., 85-121 (1997).

[0034] 10. J. H. Burroghes, et al., Nature 374, 529 (1990).

[0035] 11. Y. Z. Wang, A. J. Epstein, et al., Color VariableLight-Emitted Devices Based on Conjugated Polymers, Appl. Phys. Lett.70, 3215-3217 (1997).

[0036] 12. A. J. Epstein and Y. Z. Wang, Interface Control ofLight-Emitted Devices Based on Pyridine-Containing Conjugated Polymers,Acc. Chem Res. 32, 217-224 (1999); R. G. Sun, A. J. Epstein, et al.,1.54 μm IR PL and EL from an Er Organic Compound, J. Appl. Phys. 87,7589-7591 (2000).

[0037] 13. See, for example, CDT website: www.cdtltd.co.uk.

[0038] 14.S. Chitteppeddi, K. R. Cromack, J. S. Miller, and A. J.Epstein, Ferromagnetism in Molecular DecamethylferroceniumTetracyanoethenide, Phys. Rev. Lett. 58, 2695-2998 (1987).

[0039] 15. K. I. Pokhodnya, A. J. Epstein, and J. S. Miller, LowTemperature (40 C) Chemical Vapor Deposition of Thin Film of Magnets,Adv. Mat. 12, 410-413 (2000).

[0040] 16. Z. H. Wang, A. J. Epstein, et al., Transport and EPR Studiedof Polyaniline: A Quasi-One-D Conductor with Three-Dimensional“Metallic” States, Phys. Rev. B 45, 4190-4202 (1992).

[0041] 17. J. Joo, A. J. Epstein, et al. Charge Transport of MesoscopicMetallic State in Partially Crystalline Polyanilines, Phys. Rev. B 57,9567-9580 (1998).

[0042] 18. S. M. Long, P Zhou, J. S. Miller, and A. J. Epstein, EPRStudy of the Disorder in V(TCNE)_(X) y(MeCN) High-T_(c) Molecule-BasedMagnet, Mol. Cryst. Liq. Cryst. 272, 207-215 (1995).

[0043] 19. R. S. Kohiman, A. J. Epstein, et al., Limits for MetallicConductivity in Conducting Polymers, Phys. Rev. Lett. 78, 3915-3118(1997); C. J. Bolton-Heaton, V. N. Prigodin and A. J. Epstein, et al.,Distribution of Time Constanst for Tunneling through a 1D DisorderedChain, Phys. Rev. B 60, 10569-10573 (1999); A. N. Samukhin, V. N.Prigodin, L. Jastrabik, and A. J. Epstein, Hopping Conductivity of aNearly 1D Fractal: A Model for Conducting Polymers, Phys. Rev. B 58,11354-11370 (1998).

[0044] 20.J. M. Yeomans, Statistical Mechanics of Phase Transitions,Oxford Univ. Press, N.Y., 1992.

[0045] 21. L. Pu, Chiral Conjugated Polymers, Acta Polymerica 48,116-141 (1997); E. Peters, et al., Circularly Polarized EL from aPolymer LED, J. Am. Chem. Soc. 119, 9909-9910 (1997).

[0046] 22. E. Charney, The Molecular Basis of Optical Activity: OpticalRotary Dispersion and Circular Dichroism, Wiley-Interscience,Chichester, 1979.

[0047] The foregoing references are hereby incorporated herein byreference.

[0048] The preferred embodiments herein disclosed are not intended to beexhaustive or to unnecessarily limit the scope of the invention. Thepreferred embodiments were chosen and described in order to explain theprinciples of the present invention so that others skilled in the artmay practice the invention. Having shown and described preferredembodiments of the present invention, it will be within the ability ofone of ordinary skill in the art to make alterations or modifications tothe present invention, such as through the substitution of equivalentmaterials or structural arrangements, or through the use of equivalentprocess steps, so as to be able to practice the present inventionwithout departing from its spirit as reflected in the appended claims,the text and teaching of which are hereby incorporated by referenceherein. It is the intention, therefore, to limit the invention only asindicated by the scope of the claims and equivalents thereof.

What is claimed is:
 1. A spintronic device comprising: (1) a firstelectrical contact; (2) a first magnetic component in contact with saidfirst electrical contact and having a first coercive field associatedtherewith; (3) a non-magnetic conductive, semi-conductive, or insulatingcomponent in contact with said hard magnetic component; and (4) a secondmagnetic component in contact with said non-magnetic conductive,semi-conductive, or insulating component, and having coercive field lessthan said first coercive field; and (5) a second electrical contact incontact with said polymeric, molecular or organic-based magneticcomponent; wherein at least one of said first and second magneticcomponents is a polymeric, molecular or organic-based magneticcomponent.
 2. The spintronic device according to claim 1 wherein saidnon-magnetic conductor or semi-conductor is selected from the groupconsisting of conductive polymers.
 3. The spintronic device according toclaim 2 wherein said conductive polymer is selected from the groupconsisting of doped or undoped polyanilines, polythiophene,polypyrroles, Polyphenylenevinylenes and polyparaphenylenes andderivatives and mixtures thereof.
 4. The spintronic device according toclaim 1 wherein said non-magnetic conductor or semi-conductor isselected from the group consisting of organic or molecular electricallyconductive complexes.
 5. The spintronic device according to claim 4wherein said organic or molecular electrically conductive complexes areselected from the group consisting of doped or undoped oligomers, andcharge transfer salts.
 6. The spintronic device according to claim 5wherein said doped oligomers are selected from the group consisting ofdoped tetraaniline and doped 6-thiophene, and oligomers thereof.
 7. Thespintronic device according to claim 1 wherein said non-magneticconductor or semi-conductor is selected from the group consisting ofdoped polyaniline, doped polythiophene or organic or molecularelectrically conductive complexes selected from the group consisting ofcharge transfer salts.
 8. The spintronic device according to claim 7wherein said charge transfer salts are selected from the groupconsisting of salts and alkali metal salts of tetracyanoquinodimethne[TCNQ], salts of tetrathiofulvalene [TTF] with halide counter ions,TTF-TCNQ, salts of perylene and derivatized and benzene ring-extendedstructures thereof, and those with repeating perylene units, andderivatives thereof wherein the counter ions include PF₆, BF₄, ClO₄ andhalides.
 9. The spintronic device according to claim 1 wherein saidnon-magnetic insulating component is selected from the group consistingof insulating polymers.
 10. The spintronic device according to claim 9wherein said insulating polymer is selected from the group consisting ofpolymethylmethacrylates, polyethylenes, polytetrafluoroethylenes,polyvinyl carbazoles, polydiphenylacetylenes, and derivatives andmixtures thereof.
 11. The spintronic device according to claim 1 whereinsaid non-magnetic insulating component is selected from the groupconsisting of molecular insulators.
 12. The spintronic device accordingto claim 11 wherein said molecular insulator is selected from the groupconsisting of acene oligomers, naphthacene, anthacene, tetracene,pentacene, sexi-acene, hepta-acene, perylene, oligomers of stilbene,oligomers of phenylene, TTF and TCNQ, and oligomers of thiophene. 13.The spintronic device according to claim 1 wherein said non-magneticconductor or semi-conductor is selected from the group consisting ofelemental binary or alloy inorganic metals.
 14. The spintronic deviceaccording to claim 13 wherein said elemental binary or alloy inorganicmetals are selected from the group consisting of copper, silver, gold,lead, lithium, aluminum and lithium:aluminum alloys.
 15. The spintronicdevice according to claim 1 wherein said non-magnetic semi-conductor isselected from the group consisting of silicon, germanium, GaAs, GaN, andthe p- and n-doped forms thereof.
 16. The spintronic device according toclaim 1 wherein said non-magnetic insulator is selected from the groupconsisting of aluminum oxide and titanium dioxide.
 17. A spintronicdevice comprising: (1) a first electrical contact; (2) a polymeric,molecular or organic-based conductive magnetic component in contact withsaid first electrical contact and capable of producing a spin polarizedcurrent; (3) a light emitting polymer or molecular material capable ofproducing circularly polarized light and in contact with said conductivemagnetic component; and (4) a second electrical contact in contact withsaid light emitting polymer.
 18. The spintronic device according toclaim 17 additionally comprising a substrate.
 19. The spintronic deviceaccording to claim 17 additionally comprising a source of electricalcurrent.
 20. The spintronic device according to claim 17 wherein saidfirst electrical contact acts as an anode and said second electricalcontact acts as a cathode.
 21. The spintronic device according to claim20 wherein said anode is optically transmissive.
 22. The spintronicdevice according to claim 20 wherein said anode is opticallynon-transmissive.
 23. The spintronic device according to claim 20wherein said anode is selected from the group consisting of ITO, gold,doped polyanilines and derivatives thereof, and doped polythiophenes andderivatives thereof, and mixtures and multi-layers thereof.
 24. Thespintronic device according to claim 20 wherein said cathode isoptically transmissive.
 25. The spintronic device according to claim 20wherein said cathode is optically non-transmissive.
 26. The spintronicdevice according to claim 20 wherein said cathode is selected from thegroup consisting of aluminum, magnesium, calcium, lithiumm:aluminumalloys.
 27. The spintronic device according to claim 17 wherein saidfirst electrical contact acts as a cathode and said second electricalcontact acts as an anode.
 28. The spintronic device according to claim27 wherein said anode is light transmissive.
 29. The spintronic deviceaccording to claim 27 wherein said anode is light non-transmissive. 30.The spintronic device according to claim 27 wherein said anode isselected from the group consisting of ITO, gold, doped polyanilines andderivatives thereof, and doped polythiophenes and derivatives thereof,and mixtures and multi-layers thereof.
 31. The spintronic deviceaccording to claim 27 wherein said cathode is optically transmissive.32. The spintronic device according to claim 27 wherein said cathode isoptically non-transmissive.
 33. The spintronic device according to claim27 wherein said cathode is selected from the group consisting ofaluminum, magnesium, calcium, lithiumm:aluminum alloys.
 34. Thespintronic device according to claim 17 wherein said polymeric,molecular or organic-based conductive magnetic component is selectedfrom the group consisting of M[TCNE]_(X) where TCNE istetracyanoethylene and x is 1 to 2.5; preferably 1.8 to 2.2; and whereinM is selected from the group consisting of Mn, V, and Fe; and PrussianBlue(s) structure-containing compounds.
 35. The spintronic deviceaccording to claim 17 wherein said polymeric, molecular or organic-basedconductive magnetic component is selected from the group consisting ofM[TCNQ]_(X) where TCNQ is tetracyanoquinodimethane and x is 1 to 2.5;preferably 1.8 to 2.2; and wherein M is selected from the groupconsisting of Mn, V, and Fe; and Prussian Blue(s) structure-containingcompounds.
 36. The spintronic device according to claim 17 wherein saidlight emitting polymer or molecular material is selected from the groupconsisting of erbium-, platinum-, iridium-containing polymers andmolecular materials containing rare earth or transition metals.
 37. Thespintronic device according to claim 36 wherein said rare earth ortransition metals are selected from the group consisting of erbium,holmium, terbium, europium neodymium, platinum and iridium.
 38. Thespintronic device according to claim 1 wherein said polymeric, molecularor organic-based magnetic component is selected from the groupconsisting of M[TCNE]_(X) where TCNE is tetracyanoethylene and x is 1 to2.5; preferably 1.8 to 2.2; and wherein M is selected from the groupconsisting of Mn, V, and Fe; and Prussian Blue(s) structure-containingcompounds.
 39. The spintronic device according to claim 1 wherein saidpolymeric, molecular or organic-based magnetic component is selectedfrom the group consisting of M[TCNQ]_(X) where TCNQ istetracyanoquinodimethane and x is 1 to 2.5; preferably 1.8 to 2.2; andwherein M is selected from the group consisting of Mn, V, and Fe; andPrussian Blue(s) structure-containing compounds.
 40. The spintronicdevice according to claim 1 wherein said hard magnetic component isselected from the group consisting of AlNiCo magnets, ferrous magnets,nickel-based magnets and cobalt-based magnets.
 41. A spintronic devicecomprising: (1) a first electrical contact; (2) a first polymeric,molecular or organic-based magnetic component in contact with said firstelectrical contact and having a first magnetic field associatedtherewith; (3) a non-magnetic conductive, semi-conductive, or insulatingcomponent in contact with said first polymeric, molecular ororganic-based magnetic component; (4) a second polymeric, molecular ororganic-based magnetic component in contact with said non-magneticconductive, semi-conductive, or insulating component, and having asecond magnetic field associated therewith; and (5) a second electricalcontact in contact with said second polymeric, molecular ororganic-based magnetic component; and (6) a source of a magnetic fieldpositioned so as to increase the strength of said second magnetic fieldabove that of said first magnetic field.
 42. The spintronic deviceaccording to claim 41 additionally comprising a source of a switchablemagnetic field adapted to vary the direction of magnetization of saidfirst polymeric, molecular or organic-based magnetic component so as toalter the ability of said device to carry current.
 43. The spintronicdevice according to claim 1 additionally comprising a source of aswitchable magnetic field adapted to vary the direction of magnetizationof said second magnetic component, so as to alter the ability of saiddevice to carry current.
 44. A spintronic device comprising: (1) anon-magnetic conductive or semi-conductive component defining a currentconduit; (2) a first electrical contact and a second electrical contacteach in contact with said non-magnetic conductive or semi-conductivecomponent so as to define a current direction therebetween; (3) a firstmagnetic component on one side of said current conduit and in contactwith said non-magnetic conductive or semi-conductive component, andhaving a first magnetic field associated therewith; and (4) a secondmagnetic component on another side of said current conduit and incontact with said non-magnetic conductive or semi-conductive component,and having a second magnetic field associated therewith; and (5) asource of a switchable magnetic field adapted to vary the direction ofmagnetization of said second magnetic component so as to alter theability of said current conduit to carry current; wherein at least oneof said first and second magnetic components is a polymeric, molecularor organic-based magnetic component.
 45. The spintronic device accordingto claim 44 wherein both of said first and second magnetic components isa polymeric, molecular or organic-based magnetic component, andadditionally comprising a source of a magnetic field positioned so as toincrease make said second magnetic field larger than said first magneticfield.
 46. A spin field effect transistor comprising: (1) asemiconductor; (2) a source material in contact with said semiconductor;(3) a drain material in contact with said semiconductor; said source anddrain materials comprising a conductive magnetic material, at least oneof which is a polymeric, molecular or organic-based magnetic material.47. A spin field effect transistor according to claim 46 additionallycomprising a gate material in contact with said semiconductor.
 48. Aspin field effect transistor according to claim 46 additionallycomprising a source of a magnetic field positioned so as to modulate themagnetization of said source material with respect to said drainmaterial.
 49. A spin field effect transistor according to claim 48additionally comprising a gate material in contact with saidsemiconductor.
 50. A spin field effect transistor according to claim 46additionally comprising a source of a magnetic field positioned so as tomodulate the magnetization of said drain material with respect to saidsource material.
 51. A spin field effect transistor according to claim50 additionally comprising a gate material in contact with saidsemiconductor.